Field of the Invention
[0001] The present invention relates to a probe for detecting abnormality of internal tissue
utilizing fiber optic means, and more particularly, to a probe for a spectrum analysis
of reflected light by living tissue or organ of human which are kept in touch with
it. The probe of the present invention can be inserted within human body through an
opening of endoscopic device without difficulty.
Prior Art
[0002] The method and its principle for measuring absorbance of light which is projected
on human tissue or more practically those for spectrum-analysis of the reflected beam
from the tissue to be observed are shown in Fig. 1. the corresponding data-processing
flow is shown in Fig. 2. In Fig. 1 and Fig. 2, a probe 1 consists of optical fiber
light-guide 2 and 3, in which the former is for projecting light beam on to surface
of an tissue and the latter is for receiving the reflected beams therefrom. As shown
in Fig. 1 the two optical wave-guides are combined together to form a unified bundle
5 of optical fibers within a protective sheath 4 in their one end portion whose cross-sectional
(radial cross-section) portion 6 faces the object tissue.
[0003] The other end portion of the two groups of optical fibers 2 and 3 are kept separated
and a light source 8, focusing lens 9 are connected to one of the bundles 2, while
the remaining light-receiving optical fibers 3 are connected to a spectral apparatus
12 containing a spectrum-diffraction device 10, and an image sensor array 11.
[0004] The circular end portion 6 faces the object tissue and its surface is illuminated
by beams from light source 8 through focussing lens 9 and optical waveguide 2. The
reflective light beams are transmitted to the spectral apparatus 12 where their spectroscopic
analysis is carried out. The results of the analysis are displayed either on a cathode
ray tube (CRT) or printed by a graphic printer.
[0005] Fig. 3 illustrates configuration of such a probe for practical diagnostic use. A
connector portion is formed where the branching portion of the bundle into two fiber
waveguides 2 and 3 are included. To each of the divided waveguides 2 and 3 metal connecting
plug 19 and 20 are attached. The probe 1 in the figure is connected to light source
8 and to spectral apparatus 12 by means of connecting portion 18.
[0006] In order to achieve an accurate measurement by utilizing such a probe as described
above, it is necessitated that the annular contact surface of the probe is in an appropriate
state of contact with the object tissue portion.
[0007] A method of observing a good contact of the sensing surface of the probe with the
object tissue surface is shown in Fig. 4. An electrode 15 is attached to the object
human body 14 for grounding purpose and weak electric current with high frequency
is applied between the electrode 15 and a sleeve 16 which is attached to an end portion
of the probe. The value of impedance measured when a sleeve 16 is in contact with
human body 14 is taken as an index of the degree of contact between them. A circuit
for detecting such an index is illustrated in Fig. 5 and some configurational view
of the sleeve 16 and a lead-wire 17 shown in Fig. 6.
[0008] Problems arise from the fact that the measuring probe for spectrum analysis of human
tissue is usually applied together with an endoscope having some small opening called
"a forceps window" through which the probe is lead into human body until it reaches
to the surface of the object tissue. As the sleeve 16 is placed around the outer circumference
of an end portion of the probe, the radius of that end portion will become larger
than usual. For instance in the case of gastroscopic analysis, the surface of the
object tissue is gastro-mucous membrane and it causes difficulties for phycicicion
to apply a probe with such an outside sleeve into stomach through an opening originally
designed for inserting forceps.
[0009] These difficulties are further increased by the fact that the lead wire 17 is wired
outwardly along the probe separately which also leads to enlargement of the probe
and diminishes its operability.
[0010] The problem underlying the invention is therefore to provide a probe capable of detecting
the degree of contact with an object human tissue and of being introduced through
openings for forceps in an endoscopic configuration into human body without difficulty.
[0011] The solution of this problem is achieved by the characterizing features of claims
1 and 2.
Summary of the Invention
[0012] According to the present invention a probe is provided comprising a metal ring which
has about the same outer diameter as the fiber bundle with sheath. Said metal ring
is placed around the circumferencial surface of the measuring end portion of the probe
and is electrically connected with either one of metal tips attached to optical fiber
wave guides for light projection or the ones for receiving reflected light beams from
the object tissue.
Brief Description of the Drawings
[0013] The invention will now be described by way of example, with reference to the accompanying
drawings in which:
Fig. 1 shows a whole scope of the spectro-analyzer for human tissue utilizing an optical
probe in general.
Fig. 2 shows total functional featurs of the spectro-analyzer utilizing an optical
probe in general.
Fig. 3 illustrates a schematic view of an optical probe in general.
Fig. 4 shows a method of detecting degree of contact of an optical probe with human
tissue.
Fig. 5 shows circuit for measuring contact impedance as a measure of the aegree of
contact of an optical probe with human tissue.
Fig. 6 shows constraction of conventional type of optical probe which carries lead
wire separately.
Fig. 7 shows a longitudinal cross-section of an embodiment of the probe of the present
invention.
Fig. 8 shows a cross-sectional view of the probe illustrated in Fig. 7 along line
A-A.
Description of the Preferred Embodiments
[0014] Fig. 7 shows a longitudinal cross-section of the probe of the present invention and
Fig. 8 shows also a cross-sectional view of the probe of the present invention which
is taken at the plane corresponding to A-A in Fig. 7. The probe 23 has basicly similar
configuration to the one shown in Fig. 3.
[0015] Optical fiber waveguide for sending projection beams 2 and those for receiving reflected
beams 3 are bundled together within a covering layer to form one bundle of optical
fibers 5 in a common protective sheath 4 and its one end portion becomes the measuring
end portion 6.
[0016] The bundled fibers are divided again at the connecting portion 18 into former two
waveguide parts of 2 and 3 and metal tips 19 and 20. are connected to each of them
respectively. In the probe of the present invention, the measuring end portion 6 of
the probe has a metal ring 21 at its end portion of almost equal outer diameter as
that of the fiber bundle 5 with sheath layer instead of protective sheath 4.
[0017] The inside circumferential surface of the metal ring 21 directly contacts with the
outer circumference of the fiber bundle 5 in its longitudinal direction and shares
one common plane 6 in its radial direction, so that the metal ring 21 has a core portion
which is composed of optical fibers as shown in Fig. 8.
[0018] The outer surface of the metal ring 21 has been shaped so that its outer diameter
diminishes stepwisely, and is fixed under the protective sheath 4. As illustrated
in Fig. 8, at least one metalic lead wire 22 is located in the fiber bundle 5 under
the protective sheath 4 and is incorporated into either of the optical fiber waveguide
for receiving reflected beams 3 or for sending projection beam. Then the metal ring
21 can be electrically connected to either of the metal connecting plug 19 or 20 by
means of lead wire 22. The lead wire 22 can be designed so as to be enough fine to
transmit very weak electrical signals while keeping the outer diameter of the fiber
bundle unchanged.
[0019] By connecting the metal connecting plug 20 with terminal T in Fig. weak elf oric
-urrent of high frequency will be transmitted through lead wire 22 to the metal ring
21 which is placed around the circumferential surface of the maasuring end portion
6 of the probe 23 and thus the electric current is transferred between electrode for
grounding 15 and metal ring 21 when the measuring end portion 6 has become attached
to the surface of the object tissue 13. The observed value of contact impedance provides
an indication of the degree of contact between the probe and the object tissue.
[0020] As described above, the present invention provides an improved probe for detecting
abnormality of living tissue by spectre-analytical principle which allows its handling
with conventional endoscopes with opening for forceps and is capable of assuring steady
contact of its measuring end portion to the object tissue.
1. A probe for detecting abnormality of internal tissue by spectroscopic method having
a bundle of optical fibers (5) whose one end is used as measuring end portion (6)
and the other end portion is incorporated in a connecting portion (18) where the bundle
is divided into two groups (2, 3), namely one for transmission of the projection light
beams to an object tissue (13) and the other for receiving reflected light beams from
the object tissue, characterized by comprising a connecting plug of metal on each
end of the optical fibers (2, 3), and a metal ring (21) placed on the circumference
of the measuring end portion (6) to which an electrical contact with the object tissue
is made by means of at least one lead wire (22) and one of said connecting plug of
met al (20, 19) so that the degree of contact of the measuring surface of the probe
(6) with object tissue (13) can be continuously observed in order to assure stable
measurement of the object.
2. A probe for detecting abnormality of internal tissue by spectroscopic method utilizing
optical fibers comprising:
a bundle of optical fibers (5) in which two groups of optical fibers (2, 3), namely
a group of optical fibers for transmitting light beams for projection of an object
tissue surface (13) and the other group of optical fibers for transmitting reflected
light beams from the projected tissue surface (13) under observation;
a cover layer for protecting the bundle of fibers forming a sheath (4) over the fiber
bundle (5);
a connecting portion (18) in which said two groups of optical fibers (2, 3) are divided
into two independent groups of optical fibers of light-projecting and of light-receiving
purposes having a connecting plug of metal (19, 20) on each end portion of said separated
group of optical fibers;
characterized by further comprising
a metal ring (21) placed around the circumference of the measuring end portion (6)
of said bundle of optical fibers (5), in a way that the outer diameter of the metal
ring (21) does not exceed that of the bundle of optical fibers (5) covered by the
protective sheath (4) by attaching the metal after removing the sheath portion lying
under the metal ring off the surface of the bundle;
and at least one lead wire (22) which is bundled together with the optical fibers
for the purpose of making electrical connection between the metal ring (21) on the
circumference of the measuring end portion (6) of the bundle of optical fibers (5)
and either one of the connecting plug of metal (19, 20) attached to the other branched
end portions of the bundle.